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evaluate.c
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/* Asp applicative langauge
* J.Cupitt, November 86
* The evaluator. Necessary fuzzy int/pointer stuff hated by lint. */
#include "asphdr.h" /* Get global header */
#include "evaltypes.h" /* Runtime types */
#include "lextypes.h" /* Needed by symboltypes */
#include "parsetypes.h" /* Needed by symboltypes */
#include "symboltypes.h" /* Get types we manipulate */
#include "error.h" /* Need error handling */
#include "io.h" /* Need line numbers */
#include "memory.h" /* Need memory allocation */
#include "dump.h" /* Get prettyprinter */
#include "declare.h" /* Need ScriptRoot */
#include "main.h" /* Need stack defaults */
#include "list.h" /* List handling macros */
#include "pointermacros.h" /* Pointer following macro */
int NumberReductions = 0; /* Number of reductions we do */
/* These two are exported to the memory handler. It needs to scan these during relocation */
struct EvalNode **Stack; /* Runtime argument stack */
int sp; /* Stack pointer */
static int spfence; /* What we cannot reduce below. */
static int *FenceStack; /* Stack of past fences */
static int fsp; /* Fence stack */
/* Stack of pointers to C pointers into the heap. Exported to the memory .
* relocator. This is why we can't have register variables all the time! */
struct EvalNode ***PointerStack;
int psp;
static struct Pointer Reduce(); /* Need to forward ref these */
static void PrettyLeft();
static void PrettyRight();
static enum Boolean EqualRightRight();
static enum Boolean EqualLeftLeft();
static void ForceLeft();
static void ForceRight();
#define MAXFILENAME 1024 /* Max length of name for READ */
/* Macros for argument stack manipulation. */
#define PUSH(A) {Stack[sp++]=(A);if(sp>AStackSize){errorstart();\
errorstr( "arg stack full" ); errorend(); quit(); }}
#define POP (Stack[--sp])
/* Macros for manipulating the pointer stack. */
#define PPUSH(A) {PointerStack[psp++]=(&(A));if(psp>PStackSize){errorstart();\
errorstr( "pstack full" ); errorend(); quit(); }}
#define PPOP (--psp)
/* More macros for pointer following etc. */
#define FRCELL(A) ((A)->tag=FREE)
#define FREENODE(A) ( ((--(A)->refcount)==0)?(FRCELL(A),TRUE):(FALSE) )
#define CALLIFPOINTER(A,B) {if((A)->tag==ABSOLUTE){(B)(INDIRECTABS(A));} else if((A)->tag==RELATIVE){(B)(INDIRECTREL(A));};}
#define REDPOINT(A) {if((A).tag==ABSOLUTE) (A)=Reduce(INDIRECTABS(&A)); else if((A).tag==RELATIVE) (A)=Reduce(INDIRECTREL(&A));}
/* Macros for fence stack manipulation */
#define PUSHFENCE {if(fsp>FStackSize){ errorstart();\
errorstr( "fstack full" ); errorend(); quit(); };\
FenceStack[fsp++]=spfence; spfence=sp; }
#define POPFENCE {if(sp != (spfence=FenceStack[--fsp])){\
errorstart(); errorstr( "args unused" ); errorend(); quit(); };}
/* Making and clearing fences */
#define FENCERED(A) {if(sp!=spfence){PUSHFENCE;REDPOINT(A);POPFENCE;}\
else REDPOINT(A);}
/* Error on stack allocation */
static void memerr()
{ errorstart();
errorstr( "unable to allocate space for eval stacks" );
errorend();
quit();
};
/* Initialise the stacks we use. Sizes are set by main.c from CL flags.
* Exported */
void InitEvalStacks()
{ Stack = (struct EvalNode **)
malloc( AStackSize * sizeof(struct EvalNode *) );
if( Stack == NULL )
memerr();
FenceStack = (int *)
malloc( FStackSize * sizeof(int) );
if( FenceStack == NULL )
memerr();
PointerStack = (struct EvalNode ***)
malloc( PStackSize * sizeof(struct EvalNode **) );
if( PointerStack == NULL )
memerr();
/* Clear all the stacks */
sp = fsp = psp = spfence = 0;
};
/* Help with error messages */
static void typeerror( op, should )
char *op, *should;
{ errorstart();
errorstr( "args to " );
errorstr( op );
errorstr( " should be " );
errorstr( should );
errorend();
quit();
};
/* Free a node recursivly */
static void FreeMultiple( n )
register struct EvalNode *n;
{ /* No need to declare the EvalNode ... */
#ifdef DEBUG
printf( "Freeing multiple ...\n" );
#endif
if( --n->refcount == 0 )
switch( n->tag ) {
case GEN1:
case READ:
case ERROR:
case CODE:
case DECODE:
case IDENTITY:
case UNARYMINUS:
case NOT:
case HD:
case TL:
CALLIFPOINTER(&n->left,FreeMultiple);
FRCELL( n );
return;
case WRITE:
case GEN2:
case GEN3:
case GEN4:
case AND:
case OR:
case CONS:
case BINARYPLUS:
case BINARYMINUS:
case TIMES:
case DIVIDE:
case LESS:
case MORE:
case EQUAL:
case MOREEQUAL:
case LESSEQUAL:
case NOTEQUAL:
case IF:
case APPLICATION:
CALLIFPOINTER(&n->left,FreeMultiple);
CALLIFPOINTER(&n->right,FreeMultiple);
FRCELL( n );
return;
case STREAM:
/* More complicated -- have to close
* the file. */
{ FILE *fd;
fd = (FILE *) n->left.data;
fclose( fd );
FRCELL( n );
return;
};
case HEADLAMBDA:
case LAMBDA:
FRCELL( n );
FRCELL( INDIRECT( &n->right ) );
CALLIFPOINTER( &INDIRECT(&n->right)->right,
FreeMultiple );
FreeMultiple( INDIRECT( &n->right )+1 );
return;
case FREE:
/* May sometimes happen legally ... see
* EQUAL in Reduce. */
return;
default:
errorstart();
errorstr( "broken in FreeMultiple" );
errorend();
quit();
};
};
/* Test two pointers for equality. Cannot common up structures if equal!
* (would confuse reference counting). Pass two pointers to EvalNodes and
* (in this version) test the LH pointers. Have to be careful about compaction
* under our feet! */
static enum Boolean EqualLeftLeft( a, b )
struct EvalNode *a, *b;
{ register struct Pointer *c, *d; /* Cache in here .. */
#ifdef DEBUG
printf( "Starting EqualLeftLeft...\n" );
#endif
PPUSH(a); PPUSH(b); /* Register pointers */
FENCERED(a->left); /* Reduce the two pointers */
FENCERED(b->left);
PPOP; PPOP;
c = &a->left; d = &b->left; /* Read answer into regs */
switch( c->tag ) {
case NUM:
return( (enum Boolean) (
(d->tag == NUM) &&
(c->data == d->data) ) );
case CHAR:
return( (enum Boolean) (
(d->tag == CHAR) &&
((char) c->data == (char) d->data) ) );
case BOOL:
return( (enum Boolean) (
(d->tag == BOOL) &&
((enum Boolean) c->data ==
(enum Boolean) d->data) ) );
case NIL:
return( (enum Boolean) (
(d->tag == NIL) ) );
case ABSOLUTE:
if( ISPOINTER(d) ) {
if( INDIRECTABS(c)->tag != CONS ||
INDIRECT(d)->tag != CONS ) {
errorstart();
errorstr( "= applied to a function" );
errorend();
quit();
};
return( (enum Boolean) (
EqualLeftLeft( INDIRECTABS(c),
INDIRECT(d) ) &&
EqualRightRight( INDIRECTABS(c),
INDIRECT(d) )
) );
};
return( FALSE );
case RELATIVE:
if( ISPOINTER(d) ) {
if( INDIRECTREL(c)->tag != CONS ||
INDIRECT(d)->tag != CONS ) {
errorstart();
errorstr( "= applied to a function" );
errorend();
quit();
};
return( (enum Boolean) (
EqualLeftLeft( INDIRECTREL(c),
INDIRECT(d) ) &&
EqualRightRight( INDIRECTREL(c),
INDIRECT(d) )
) );
};
return( FALSE );
default:
errorstart();
errorstr( "Broken in equal" );
errorend();
quit();
};
};
/* Test two pointers for equality. Pass two pointers to EvalNodes and
* (in this version) test the RH pointers. */
static enum Boolean EqualRightRight( a, b )
struct EvalNode *a, *b;
{ register struct Pointer *c, *d; /* Cache in here .. */
#ifdef DEBUG
printf( "Starting EqualRightRight ...\n" );
#endif
PPUSH(a); PPUSH(b); /* Register pointers */
FENCERED(a->right); /* Reduce the two pointers */
FENCERED(b->right);
PPOP; PPOP;
c = &a->right; d = &b->right; /* Read answer into regs */
switch( c->tag ) {
case NUM:
return( (enum Boolean) (
(d->tag == NUM) &&
(c->data == d->data) ) );
case CHAR:
return( (enum Boolean) (
(d->tag == CHAR) &&
((char) c->data == (char) d->data) ) );
case BOOL:
return( (enum Boolean) (
(d->tag == BOOL) &&
((enum Boolean) c->data ==
(enum Boolean) d->data) ) );
case NIL:
return( (enum Boolean) (
(d->tag == NIL) ) );
case ABSOLUTE:
if( ISPOINTER(d) ) {
if( INDIRECTABS(c)->tag != CONS ||
INDIRECT(d)->tag != CONS ) {
errorstart();
errorstr( "= applied to a function" );
errorend();
quit();
};
return( (enum Boolean) (
EqualLeftLeft( INDIRECTABS(c),
INDIRECT(d) ) &&
EqualRightRight( INDIRECTABS(c),
INDIRECT(d) )
) );
};
return( FALSE );
case RELATIVE:
if( ISPOINTER(d) ) {
if( INDIRECTREL(c)->tag != CONS ||
INDIRECT(d)->tag != CONS ) {
errorstart();
errorstr( "= applied to a function" );
errorend();
quit();
};
return( (enum Boolean) (
EqualLeftLeft( INDIRECTREL(c),
INDIRECT(d) ) &&
EqualRightRight( INDIRECTREL(c),
INDIRECT(d) )
) );
};
return( FALSE );
default:
errorstart();
errorstr( "Broken in equal" );
errorend();
quit();
};
};
/* Test two pointers for equality. Pass two pointers to EvalNodes and
* (in this version) test the LH against the RH. Called only from Reduce. */
static enum Boolean EqualLeftRight( a, b )
struct EvalNode *a, *b;
{ register struct Pointer *c, *d; /* Cache in here .. */
#ifdef DEBUG
printf( "Starting EqualLeftRight ...\n" );
#endif
PPUSH(a); PPUSH(b); /* Register pointers */
FENCERED(a->left); /* Reduce the two pointers */
FENCERED(b->right);
PPOP; PPOP;
c = &a->left; d = &b->right; /* Read answer into regs */
switch( c->tag ) {
case NUM:
return( (enum Boolean) (
(d->tag == NUM) &&
(c->data == d->data) ) );
case CHAR:
return( (enum Boolean) (
(d->tag == CHAR) &&
((char) c->data == (char) d->data) ) );
case BOOL:
return( (enum Boolean) (
(d->tag == BOOL) &&
((enum Boolean) c->data ==
(enum Boolean) d->data) ) );
case NIL:
return( (enum Boolean) (
(d->tag == NIL) ) );
case ABSOLUTE:
if( ISPOINTER(d) ) {
if( INDIRECTABS(c)->tag != CONS ||
INDIRECT(d)->tag != CONS ) {
errorstart();
errorstr( "= applied to a function" );
errorend();
quit();
};
return( (enum Boolean) (
EqualLeftLeft( INDIRECTABS(c),
INDIRECT(d) ) &&
EqualRightRight( INDIRECTABS(c),
INDIRECT(d) )
) );
};
return( FALSE );
case RELATIVE:
if( ISPOINTER(d) ) {
if( INDIRECTREL(c)->tag != CONS ||
INDIRECT(d)->tag != CONS ) {
errorstart();
errorstr( "= applied to a function" );
errorend();
quit();
};
return( (enum Boolean) (
EqualLeftLeft( INDIRECTREL(c),
INDIRECT(d) ) &&
EqualRightRight( INDIRECTREL(c),
INDIRECT(d) )
) );
};
return( FALSE );
default:
errorstart();
errorstr( "Broken in equal" );
errorend();
quit();
};
};
/* Force evaluation of a structure. Used by things like READ that are strict
* in some structured argument. */
static void ForceLeft( stacknode )
struct EvalNode *stacknode;
{ PPUSH(stacknode);
FENCERED(stacknode->left);
if( ISPOINTER(&stacknode->left) ) {
stacknode = INDIRECT(&stacknode->left);
if( stacknode->tag == CONS ) {
ForceLeft( stacknode );
ForceRight( stacknode );
};
};
PPOP;
};
/* Force evaluation of a structure. Used by things like READ that are strict
* in some structured argument. */
static void ForceRight( stacknode )
struct EvalNode *stacknode;
{ PPUSH(stacknode);
FENCERED(stacknode->right);
if( ISPOINTER(&stacknode->right) ) {
stacknode = INDIRECT(&stacknode->right);
if( stacknode->tag == CONS ) {
ForceLeft( stacknode );
ForceRight( stacknode );
};
};
PPOP;
};
/* Walk a structure, building a C string. Used by things like READ and WRITE
* that take a file name as argument. Pass an EvalNode, start from it's
* LHS. Also pass a string to be used as an error message in case we hit
* a non-char.
* Assume the buffer passed is at least MAXFILENAME long. */
static void GetStringLeft( stacknode, name, err )
struct EvalNode *stacknode;
register char *name;
char *err;
{ /* Length of string collected so far */
register int p = 0;
/* Cache node pointers in here */
register struct EvalNode *node;
#ifdef DEBUG
printf( "Reducing [char]\n" );
#endif
/* Force evaluation of the argument */
PPUSH(stacknode);
ForceLeft( stacknode );
PPOP;
node = stacknode;
/* Walk down the arg, building a C string. */
if( !ISPOINTER(&node->left) )
typeerror( err, "list" );
node = INDIRECT(&node->left);
if( node->tag != CONS )
typeerror( err, "list" );
for(;;) {
if( node->left.tag != CHAR )
typeerror( err, "list of char" );
name[p++] = GETCHAR(&node->left);
if( p > MAXFILENAME ) {
errorstart();
errorstr( err );
errorstr( " arg too long" );
errorend();
quit();
};
if( node->right.tag == NIL ) {
name[p] = '\0';
break;
};
if( !ISPOINTER(&node->right) )
typeerror( err, "list" );
node = INDIRECT(&node->right);
if( node->tag != CONS )
typeerror( err, "list" );
};
};
/* Evaluate a node. Return a Pointer containing an unboxed value, a pointer
* to a lambda or a pointer to a cons node. Free up the node (unless we are
* returning a cons)
* after reducing it. Caller relinquishes all rights to node being reduced!
* Have to look out for compaction. We keep two copies of our node pointer --
* one on the stack and one in a register. Refresh the register everytime
* there is a chance the stack may have changed. */
static struct Pointer Reduce( stacknode )
struct EvalNode *stacknode;
{ register struct EvalNode *node;
/* Loop here in some cases (elimination of tail recursive calls)... */
mainloop:
#ifdef TREES
printf( "Graph on entry to Reduce\n" );
DumpGraph( 2, &ScriptRoot->details.func.code );
#endif
++NumberReductions; /* Note this reduction */
switch( (node = stacknode)->tag ) {
case IDENTITY:
#ifdef DEBUG
printf( "Identity\n" );
#endif
/* goto here at end of HD, TL, IF -- anywhere that can
* create an I node yielding the result. */
doInode:
PPUSH(stacknode);
REDPOINT( stacknode->left );
PPOP;
node = stacknode;
/* If we are unable to free ourselves after
* decrementing our count, we must up count on arg.
* as we are creating an extra pointer. */
if( !FREENODE( node ) )
ADDREF( &node->left );
return( node->left );
case GEN1:
{ register struct EvalNode *newnode;
register int n;
PPUSH(stacknode);
newnode = GetBlock( 1 );
FENCERED(stacknode->left);
PPOP;
node = stacknode;
if( node->left.tag != NUM )
typeerror( "[<n>..]", "num" );
n = GETINT(&node->left);
/* Link them up */
node->right.tag = ABSOLUTE;
node->right.data = (unsigned) newnode;
node->left.tag = NUM;
node->left.data = (unsigned) n;
node->tag = CONS;
newnode->tag = GEN1;
newnode->left.tag = NUM;
newnode->left.data = (unsigned) n+1;
newnode->refcount = 1;
goto consnode;
};
case GEN2:
{ register struct EvalNode *newnode;
register int n, lim;
PPUSH(stacknode);
FENCERED(stacknode->left);
FENCERED(stacknode->right);
PPOP;
node = stacknode;
if( node->left.tag != NUM )
typeerror( "[<n>..<n>]", "num" );
if( node->right.tag != NUM )
typeerror( "[<n>..<n>]", "num" );
n = GETINT(&node->left);
lim = GETINT(&node->right);
if( n>lim ) {
/* Time to go! Return [] */
node->left.tag = NIL;
if( !FREENODE(node) )
node->tag = IDENTITY;
return( node->left );
}
else {
PPUSH(stacknode);
newnode = GetBlock( 1 );
PPOP;
node = stacknode;
/* Link them up */
node->right.tag = ABSOLUTE;
node->right.data = (unsigned) newnode;
node->left.tag = NUM;
node->left.data = (unsigned) n;
node->tag = CONS;
newnode->tag = GEN2;
newnode->left.tag = NUM;
newnode->left.data = (unsigned) n+1;
newnode->right.tag = NUM;
newnode->right.data = (unsigned) lim;
newnode->refcount = 1;
goto consnode;
};
};
case GEN3:
{ register struct EvalNode *newnode;
register int n, step;
PPUSH(stacknode);
newnode = GetBlock( 1 );
FENCERED(stacknode->left);
FENCERED(stacknode->right);
PPOP;
node = stacknode;
if( node->left.tag != NUM )
typeerror( "[<n>,<n>..]", "num" );
if( node->right.tag != NUM )
typeerror( "[<n>,<n>..]", "num" );
n = GETINT(&node->left);
step = GETINT(&node->right);
/* Link them up */
node->right.tag = ABSOLUTE;
node->right.data = (unsigned) newnode;
node->left.tag = NUM;
node->left.data = (unsigned) n;
node->tag = CONS;
newnode->tag = GEN3;
newnode->left.tag = NUM;
newnode->left.data = (unsigned) step;
newnode->right.tag = NUM;
newnode->right.data = (unsigned) step+(step-n);
newnode->refcount = 1;
goto consnode;
};
case GEN4:
{ register struct EvalNode *newnode;
register int n, step, lim, off;
struct EvalNode *stacknode2;
stacknode2 = INDIRECT(&node->right);
PPUSH(stacknode); PPUSH(stacknode2);
FENCERED(stacknode2->left);
FENCERED(stacknode2->right);
FENCERED(stacknode->left);
PPOP; PPOP;
node = stacknode;
if( node->left.tag != NUM )
typeerror( "[<n>,<n>..<n>]", "num" );
n = GETINT(&node->left);
node = stacknode2;
if( node->left.tag != NUM )
typeerror( "[<n>,<n>..<n>]", "num" );
if( node->right.tag != NUM )
typeerror( "[<n>,<n>..<n>]", "num" );
step = GETINT(&node->left);
lim = GETINT(&node->right);
off = step-n;
if( (off>0 && n>lim) || (off<0 && n<lim) ) {
/* Time to go! Return [] */
FRCELL(node);
node = stacknode;
node->left.tag = NIL;
if( !FREENODE(node) )
node->tag = IDENTITY;
return( node->left );
}
else {
PPUSH(stacknode); PPUSH(stacknode2);
newnode = GetBlock( 1 );
PPOP; PPOP;
node = stacknode;
/* Link them up */
node->right.tag = ABSOLUTE;
node->right.data = (unsigned) newnode;
node->left.tag = NUM;
node->left.data = (unsigned) n;
node->tag = CONS;
newnode->tag = GEN4;
newnode->left.tag = NUM;
newnode->left.data = (unsigned) step;
newnode->right.tag = ABSOLUTE;
newnode->right.data = (unsigned) stacknode2;
newnode->refcount = 1;
stacknode2->left.data = (unsigned) step+off;
goto consnode;
};
};
case STREAM:
/* goto here from end of READ */
streamnode:
#ifdef DEBUG
printf( "Reducing STREAM\n" );
#endif DEBUG
{ FILE *fd;
int ch;
fd = (FILE *) node->left.data;
ch = getc( fd );
if( ch == EOF ) {
/* Tidy up */
#ifdef DEBUG
printf( "STREAM returns []\n" );
#endif DEBUG
fclose( fd );
/* Return NIL. May need to make an I node */
node->left.tag = NIL;
if( !FREENODE(node) )
node->tag = IDENTITY;
return( node->left );
}
else {
/* Make a new stream node */
register struct EvalNode *newnode;
#ifdef DEBUG
printf( "STREAM returns %c\n", ch );
#endif DEBUG
PPUSH(stacknode);
newnode = GetBlock( 1 );
PPOP;
node = stacknode;
/* Fill in fields and link it on */
newnode->tag = STREAM;
newnode->refcount = 1;
newnode->left.data = (unsigned) fd;
node->right.tag = ABSOLUTE;
node->right.data = (unsigned) newnode;
/* oldnode => cons */
node->tag = CONS;
/* Note character */
node->left.tag = CHAR;
node->left.data = (unsigned) ch;
/* Resume from CONS */
goto consnode;
};
};
case ERROR:
#ifdef DEBUG
printf( "Hit error node\n" );
#endif
fprintf( stderr, "User error - " );
PrettyLeft( stderr, node );
fprintf( stderr, "\n" );
quit();
case READ:
{ char name[ MAXFILENAME ];
#ifdef DEBUG
printf( "Reducing READ\n" );
#endif
/* Read argument */
PPUSH(stacknode);
GetStringLeft( node, name, "read" );
PPOP;
node = stacknode;
/* Free up the arg */
FreeMultiple( INDIRECT(&node->left) );
/* Make ourselves into a STREAM node */
node->tag = STREAM;
node->left.data = (unsigned) fopen( name, "r" );
if( node->left.data == NULL ) {
errorstart();
errorstr( "read of '" );
errorstr( name );
errorstr( "' fails" );
errorend();
quit();
};
/* Continue reduction from STREAM */
goto streamnode;
};
case WRITE:
{ char name[ MAXFILENAME ];
FILE *fd;
#ifdef DEBUG
printf( "Reducing WRITE\n" );
#endif
/* Read argument */
PPUSH(stacknode);
GetStringLeft( node, name, "read" );
node = stacknode;
/* Free up the name */
FreeMultiple( INDIRECT(&node->left) );
fd = fopen( name, "w" );
if( fd == NULL ) {
errorstart();
errorstr( "write to '" );
errorstr( name );
errorstr( "' fails" );
errorend();
quit();
};
/* Write the RHS expression */
PPUSH(stacknode);
PrettyRight( fd, node );
PPOP;
node = stacknode;
/* Free RHS up */
CALLIFPOINTER( &node->right, FreeMultiple );
/* Try to free ourselves */
if( !FREENODE( node ) )
node->tag = IDENTITY;
node->left.tag = BOOL;
node->left.data = (unsigned) TRUE;
return( node->left );
};
case CODE:
#ifdef DEBUG
printf( "Reducing code\n" );
#endif
PPUSH(stacknode);
FENCERED( stacknode->left );
PPOP;
node = stacknode;
if( node->left.tag != CHAR )
typeerror( "code", "char" );
node->left.data = (unsigned) GETCHAR(&node->left);
node->left.tag = NUM;
#ifdef DEBUG
printf( "Result of CODE is %d\n", GETINT(&node->left) );
#endif
/* No need for fancy count twiddling on any of these
* primitives, as we can be sure of never creating a
* boxed result. */
if( !FREENODE( node ) )
node->tag = IDENTITY;
return( node->left );
case DECODE:
#ifdef DEBUG
printf( "Reducing decode\n" );
#endif
PPUSH(stacknode);
FENCERED( stacknode->left )
PPOP;
node = stacknode;
if( node->left.tag != NUM )
typeerror( "decode", "char" );
node->left.data = (unsigned) GETINT(&node->left);
node->left.tag = CHAR;
#ifdef DEBUG
printf( "Result of DECODE is %c\n",
GETCHAR(&node->left) );
#endif
if( !FREENODE( node ) )
node->tag = IDENTITY;
return( node->left );
case UNARYMINUS:
#ifdef DEBUG
printf( "Reducing unary minus\n" );
#endif
PPUSH(stacknode);
FENCERED( stacknode->left );
PPOP;
node = stacknode;
if( node->left.tag != NUM )
typeerror( "unary minus", "num" );
node->left.data = (unsigned) -GETINT(&node->left);
#ifdef DEBUG
printf( "Result of UNARYMINUS is %d\n",
GETINT(&node->left) );
#endif
if( !FREENODE( node ) )
node->tag = IDENTITY;
return( node->left );
case NOT:
#ifdef DEBUG
printf( "Reducing not\n" );
#endif
PPUSH(stacknode);
FENCERED( stacknode->left );
PPOP;
node = stacknode;
if( node->left.tag != BOOL )
typeerror( "~", "bool" );
node->left.data = (unsigned) !GETBOOL(&node->left);
#ifdef DEBUG
printf( "Result of NOT is %s\n",
GETBOOL(&node->left)?"true":"false" );
#endif
if( !FREENODE( node ) )
node->tag = IDENTITY;
return( node->left );
case HD:
{ register struct Pointer *p;
register struct EvalNode *cons;
/* No need to PPUSH these two. */
#ifdef DEBUG
printf( "Reducing hd\n" );
#endif
PPUSH(stacknode);
FENCERED( stacknode->left );
PPOP;
node = stacknode;
if( !ISPOINTER(&node->left) )
typeerror( "hd", "list" );
/* Get a ptr to the cons node */
cons = INDIRECTABS( &node->left );
if( cons->tag != CONS )
typeerror( "hd", "list" );
/* Get a ptr to the head */
p = &cons->left;
/* Make ourselves into an I node */
node->tag = IDENTITY;
/* Copy the head up */
UNREL(p);
node->left = *p;
/* Counts:
* - One less on CONS node
* - One more on head of cons. */
if( !FREENODE(cons) )
{ ADDREF(p) }
else
CALLIFPOINTER(&cons->right,FreeMultiple);
goto doInode;
};
case TL:
{ register struct Pointer *p;
register struct EvalNode *cons;
/* Again, no need to PPUSH. */
#ifdef DEBUG
printf( "Reducing tl\n" );
#endif
PPUSH(stacknode);
FENCERED( stacknode->left );
PPOP;
node = stacknode;
if( !ISPOINTER(&node->left) )
typeerror( "tl", "list" );
/* Get a ptr to the cons node */
cons = INDIRECTABS( &node->left );
if( cons->tag != CONS )
typeerror( "tl", "list" );
/* Get a ptr to the tail */
p = &cons->right;
/* Make ourselves into an I node */
node->tag = IDENTITY;
/* Copy the tail up */
UNREL(p);
node->left = *p;
/* Counts:
* - One less on CONS node
* - One more on tail of cons. */
if( !FREENODE(cons) )
{ ADDREF(p); }
else
CALLIFPOINTER(&cons->left,FreeMultiple);
goto doInode;
};
case CONS:
/* goto here after STREAM node */
consnode:
{ register struct Pointer s;
#ifdef DEBUG
printf( "Skipping cons\n" );
#endif
/* Despite creating an extra pointer here, we do
* not need to increment any counts!
* See HD,TL,I etc. */
s.tag = ABSOLUTE;
s.data = (unsigned) node;
return( s );
};
case AND:
#ifdef DEBUG
printf( "Reducing and\n" );
#endif
PPUSH(stacknode);
FENCERED( stacknode->right );
node = stacknode;
if( node->right.tag != BOOL )
typeerror( "and", "bool" );
if( GETBOOL(&node->right) ) {
FENCERED( stacknode->left );
PPOP;
node = stacknode;
if( node->left.tag != BOOL )
typeerror( "and", "bool" );
}
else { /* Free up side we ignore */
PPOP;
CALLIFPOINTER(&node->left,FreeMultiple);
node->left.tag = BOOL;
node->left.data = (unsigned) FALSE;
};
if( !FREENODE( node ) )
node->tag = IDENTITY;
return( node->left );
case OR:
#ifdef DEBUG
printf( "Reducing or\n" );
#endif
PPUSH(stacknode);
FENCERED( stacknode->right );
node = stacknode;
if( node->right.tag != BOOL )
typeerror( "or", "bool" );
if( !GETBOOL(&node->right) ) {
FENCERED( node->left );
PPOP;
node = stacknode;
if( node->left.tag != BOOL )
typeerror( "or", "bool" );
}
else { /* Free up side we ignore */
PPOP;
CALLIFPOINTER(&node->left,FreeMultiple)
node->left.tag = BOOL;
node->left.data = (unsigned) TRUE;
};
if( !FREENODE( node ) )
node->tag = IDENTITY;
return( node->left );
case BINARYPLUS:
#ifdef DEBUG
printf( "Reducing binary plus\n" );
#endif
PPUSH(stacknode);
FENCERED( stacknode->left );
FENCERED( stacknode->right );
PPOP;
node = stacknode;
if( node->left.tag != NUM || node->right.tag != NUM )
typeerror( "+", "num" );
node->left.data = (unsigned) (
GETINT(&node->left) + GETINT(&node->right));
#ifdef DEBUG
printf( "Result of BINARYPLUS is %d\n",